1. Field of the Invention
This invention relates to a modification risk degree measurement system, a modification risk degree measurement method and a modification risk degree measurement program, which calculate, as a risk degree, the incidence rate of a possible modification result being caused as a side effect of a modification of in a program when this program is modified
2. Description of the Related Art
In a development process of software, the task of modifying a program is inevitable work. Moreover, as one of techniques for modifying the program, a technique called re-factoring is present. Re-factoring technique is a technique for improving the maintainability and extensibility of the existing program, and aims to modify module configuration, class configuration and the like without modifying a performing function of the existing program and to impart greater stability to the program.
What is always a problem in the work of modifying a program as described above is a point that, as a result of the modification in many cases, not only a modification result intended by a programmer (object modification result) is derived, but also a subordinate result not intended by the programmer (side effect result) is generated.
Various techniques have been developed in order to investigate how the side effect result generated in the work of modifying the existing program can be estimated and avoided and determine in which region of the existing program the side effect result will be generated in a case where the side effect result cannot be avoided. For example, in order to investigate the influence relationships of the respective elements in a program on this problem, a technique called “slicing” has been frequently used (See Japanese Patent Laid-Open (Kokai) No. 1994-202905, No. 1994-175884 and No. 1995-134664). “Slicing” refers to a technique for extracting a part calculating functions to be modified and unmodified functions from the existing program by use of dependency relationships and control dependency relationships in the program during modification. Meanwhile, with a view to measuring the relationships between the respective elements of the program, a technique of measuring a cohesion degree has been proposed (See Japanese Patent Laid-Open No. Hei 11 (1999)-224210). The cohesion degree indicates the extent to which function constitutional units of the program, that is, functions, methods and the like, are functionally independent, and indicates the properties of a single constitutional element unit. Quantitative evaluation of this index is broadly divided into seven stages, and the highest stage is called a “functional cohesion degree,” which indicates a program function constitutional unit capable of being provided by a single function. As a weaker cohesion degree, for example, there is a “chronological cohesion degree,” which indicates a function or the like aggregated by initialization processing. The weakest stage is called a “cryptic cohesion degree,” which indicates a program function constitutional unit where two or more unrelated functions are aggregated into one function. If the cohesion degree is used as described above, then the functions of the function and the method are measured, and quality of the program can be shown as an objective numerical value.
However, with regard to the slicing technique, though modification can be performed so as not to influence unmodified function, there have been incidences of the case where a portion to be modified is influenced by an unmodified portion therefore proper modification cannot be performed. Moreover, the obtained results have only investigated the existence of an influence relationship among the respective elements. And because it has not been possible to measure the influence degree, it has not been possible for the result of slicing to be a judgment criterion for determining a policy regarding modifying the existing program.
With regard to the technique for measuring a cohesion degree, in the work of modifying the existing program, whether or not the cohesion degree procedures are tight is not directly related to modify in the program. If the cohesion degree of the procedures is high, whether or not the measurement technique is suitable for the modifying work has not been able to be explained accurately.
Moreover, the sole solution is not present in the re-factoring plan, and there may be multiple re-factoring plans, from which a similar effect can be obtained. However, judgments for ranking re-factoring plans present in plural as optimal, suitable, and unsuitable and the like are not easy. As a result, though effectiveness of the re-factoring of the program has been recognized by general users, it has been rare that the re-factoring had been actually applied.
As described above, according to the related art, when the existing program is modified, though it is possible to estimate the side effect results of the program such as the generation of new bugs, caused by the modification, it has been difficult to measure this side effect result as an objective influence degree and to obtain information to serve as an index for flexibly planning the program alterations by use of the measurement values.
The present invention was made in consideration of the above-described problems. An object of the present invention is to provide a modification risk degree measurement system, a modification risk degree measurement method and a modification risk degree measurement program, which are capable of measuring influence degrees and influence ranges for the respective plural modification plans, calculating risk degrees from the information of this measurement, and using the risk degrees as indices when the optimal modification plan is selected from among the modification plans present in plural and to provide a modification risk measurement program.